大蒜素在正戊烷和乙醇中的分解动力学研究  

Decomposition Kinetics of Allicin in Pentane and Ethanol

作　　者：周华[1] 李文清[1] 晏日安[1] 黄雪松[1] 欧仕益[1] 

机构地区：[1]暨南大学理工学院食品科学与工程系,广东广州510632

出　　处：《现代食品科技》2013年第11期2591-2594,共4页Modern Food Science and Technology

基　　金：国家自然科学基金资助项目(31101323)

摘　　要：研究了大蒜素在正戊烷、乙醇溶剂中的分解动力学过程,拟合得到了动力学参数:大蒜素在正戊烷、乙醇溶剂中的分解活化能分别为56.0、72.0 kJ/mol,指前因子分别为9.2×105、1.5×106。采用B3LYP方法,在6-31+G(d,p)基组下计算了大蒜素与正戊烷、乙醇的相互作用能分别为1.12、31.18 kJ/mol,说明大蒜素与乙醇分子间存在较强的相互作用;采用自然键轨道理论分析了以乙醇为溶剂的体系中电子供体(Donor)轨道、电子受体(Acceptor)轨道以及它们之间相互作用的稳定化能,结果表明大蒜素分子中的氧原子的孤对电子O(13)对乙醇分子的羟基(O(21)-H(20))的反键轨道稳定化能为45.45kJ/mol,说明大蒜素与乙醇分子产生较强的氢键作用,分散了大蒜素分子中的氧原子上的负电荷,导致分子内质子转移能量升高,因而大蒜素在乙醇中具有更高热稳定性。The kinetic parameters for decomposition of allicin in pentane or ethanol were determined. The activation energies and pre-exponential factors were separately 56.0 kJ/mol and 9.2×105 in pentane as well as 72.0 kJ/mol and 1.5×106 in ethanol. The intermolecular interaction energy between allicin and solvent was calculated by density functional theory （DFT） at the B3LYP/6-31＋G（d＋P） leve1. The results showed that the intermolecular interaction energy between allicin and ethanol （31.18 kJ/mol） was higher than that between allicin and pentane （1.12 kJ/mol）. Natural orbital theory （NBO） analysis showed that the anti-bonding orbital stabilization energy between the lone pairs of O （13） in allicin and hydroxyl （O（21）-H（20）） in ethanol molecule was 45.45 kJ/mol, which illustrated that strong hydrogen bonding interaction between them dispersed the negative charges in O atom of allicin. Therefore it became more difficult in the intramolecular to transfer H atom during decomposition of allicin in ethanol.

关 键 词：大蒜素 动力学 大蒜 活化能 

分 类 号：O643.1[理学—物理化学]